A New Approach to Statistics of Cosmological Gamma-Ray Bursts

Abstract

We use a new method of analysis to determine parameters of cosmological gamma-ray bursts (GRBs), assuming that their distribution follows the star-formation history of the universe. Spectral evolution is calculated from an external shock model for fireball/blast wave evolution, and used to evaluate the measured peak flux, duration, and $\nu F_{\nu }$ peak photon energy for a GRB source occuring at a given redshift and with given values of total energy, baryon-loading and environmental parameters. We then fit model distributions of GRB sources to the observed peak flux, duration and $\nu F_{\nu }$ peak photon energy distributions. We find that the observed width of the $E_p$ and duration distributions can not be explained by cosmological redshift and time dilation effects. Rather, broad distributions of total blastwave energies and bulk Lorentz factors are necessary to explain the observed distributions simultaneously within the framework of our unifying GRB model. We discuss implications for source parameter distributions and determine a range of burst parameters consistent with the data.

22 pages, including 6 figures; uses epsf.sty, rotate.sty; now accepted for publication in ApJ; significant modifications of text and figures w.r.t. original version

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Cited by in corpus (12)

• Gamma-Ray Bursts: Progress, Problems & Prospects
• Theories of Gamma-Ray Bursts
• An analysis of gamma-ray burst spectral break models
• Expected Number and Flux Distribution of Gamma-Ray-Burst Afterglows with High Redshifts
• Beaming, Baryon-Loading, and the Synchrotron Self-Compton Component in Gamma-Ray Burst Blast Waves Energized by External Shocks
• Curvature Effects in Gamma Ray Burst Colliding Shells
• On the Redshift Distribution of Gamma Ray Bursts in the Swift Era
• Neutrino, Neutron, and Cosmic Ray Production in the External Shock Model of Gamma Ray Bursts
• High-Energy Cosmic Rays from Gamma-Ray Bursts
• A Central Engine for Cosmic Gamma-Ray Burst Sources
• High-Energy Cosmic Rays from Galactic and Extragalactic Gamma-Ray Bursts
• Cosmic Rays and High-Energy Neutrinos from Gamma-Ray Bursts